In this specification, the term “ore” is to be given a wide interpretation and includes minerals, such as coal, and the like.
In underground mining, particularly coal mining, in which continuous cutter mechanical mining machines are employed, an ore body is commonly exploited by excavating of a first series of parallel, spaced tunnels in the ore body followed by the excavation of a second series of spaced parallel tunnels, perpendicular to the first series of tunnels, thereby creating a grid-like tunnel pattern and providing spaced columns of ore, intermediate adjacent tunnels, which act as supports for the roof of the mine. The dimensions of the tunnels are generally a function of the size of the cutting head of the mechanical mining machine used in the excavation of the tunnels. The spacing between the adjacent tunnels and, consequently, the dimensions of the pillars retained in the ore body are determined by the rock mechanical structure of the mine environment and safety considerations within the environment. Amongst such safety considerations is the build-up of noxious and explosive gases within unventilated areas of the mine. In general, where a human-operated continuous cutter mining machine having a traveling cutting head is in use in the excavation of a tunnel, the lateral cross tunnels must be arranged at intervals to ensure the provision of fresh air for the operator of the machine and to exhaust noxious gases, such as methane, accumulating in the tunnel being mined, as well as exhaust gases and mining dust from the machine itself. It is commonly the case that, in the absence of artificial ventilation, the distance between cross tunnels cannot be longer than the distance between the mining head of the machine, ie the mine face, and the position of the operator on the machine. This may have the result that the percentage of the ore body extracted by mechanical mining machines in an initial series of cuts is relatively low and the mining process is inefficient.